Fire suppression systems are used extensively in office buildings, warehouses, factories, hotels, homes and other buildings and structures to provide a reliable and effective means to suppress the spread of fire throughout the building or structure. Such systems may comprise a piping network extending throughout the building. The piping network is connected to a source of fire suppressing fluid, for example, water, and is in fluid communication with sprinkler heads distributed throughout the building which will discharge the fire suppressing fluid in the event of a fire.
Each sprinkler head has a discharge orifice with a valve that is biased into a normally open position, but is held in a closed position against the biasing force by a frangible glass bulb that contains a heat-sensitive fluid. The bulb is elongate in design and the biasing force places it under compression along its long axis. The bulb is very strong in compression along its long axis but easily breaks when force is applied transverse to this axis. During a fire, the heat-sensitive fluid expands within the bulb and when a predetermined temperature is reached the heat-sensitive fluid applies hydraulic pressure outwardly against the bulb normal to the long axis, causing the bulb to shatter, and thereby allow the valve to open and discharge the fire suppressing fluid.
The bulb is designed to break at the predetermined temperature and, when installed properly, is very reliable. However, the bulb must be frangible to operate effectively and is typically made of glass which is susceptible to damage. Damage which can compromise the performance of the bulb may be caused during packing, shipping or installation of the sprinkler head and may comprise a scratch or nick in the bulb caused by a tool or another sprinkler head, as well as a crack or a small hole which allows the heat-sensitive fluid to escape. If such damage is not prevented or at least mitigated, then it is possible that the bulb may fail prematurely at a temperature lower than the predetermined temperature, thus, triggering discharge from the sprinkler head in the absence of a fire condition. This may result in extensive water damage to the building and its contents. More seriously, the damage may prevent the sprinkler head from discharging at all, as may happen if the heat-sensitive fluid is permitted to leak out. This condition will compromise the fire safety of the building and should be avoided. It is, therefore, desirable to protect such frangible items during handling, packing, shipping and installation of the sprinkler heads to ensure that they function properly when the fire suppression system is brought on line.
Proper functioning of the sprinkler head may also be prevented by foreign matter, such as paint, plaster, drywall joint compound and spackle, covering the bulb and/or discharge orifice. If the sprinkler heads are not covered when the ceiling or walls from which they protrude are being finished, for example, by painting or plastering, then it is likely that paint will be sprayed or brushed onto some sprinkler heads or plaster may coat the bulb or the orifice. This must be avoided if the sprinkler heads are to operate as intended. The problem is further complicated when recessed sprinkler heads are used, because for recessed installations, there is a greater likelihood of contamination of the sprinkler head since, being partially recessed, it is closer to the surfaces being finished.
While covers have been proposed to solve the aforementioned problems, some covers only protect the bulb from damage and leave the discharge orifice exposed to contaminants. Other covers, which protect the entire sprinkler head, do not make any provisions for using tools to install the sprinkler heads. Therefore, the installation procedure is cumbersome because the cover, initially installed over the sprinkler head for protection during shipping and handling, must be removed to allow the use of tools (typically a wrench to apply torque to a threaded nipple) for installation of the sprinkler head into the piping network. Removal of the cover to provide access for tools leaves the bulb vulnerable during installation. Furthermore, to provide protection to the sprinkler head during later finishing of the ceiling or wall, the cover must be replaced over the sprinkler head. This is often not done, the covers being lost or deliberately discarded.
There is clearly a need for an apparatus that will protect the sprinkler head from damage during shipping, and handling, will not interfere with installation or inhibit tools from being used, and will further protect the sprinkler head during finishing work, such as painting or plastering, and be readily removable to expose the sprinkler to the ambient, ready for proper operation.